(1) Field of the Invention
The present invention relates to a protective tape separation method for joining a separation tape to a surface of a protective tape joined to a surface of a semiconductor wafer while pressing a non-adhesion surface of the separation tape with a joining member and separating the separation tape, thereby separating the protective tape from the surface of the semiconductor wafer integrally with the separation. The present invention also relates to an apparatus using the method.
(2) Description of the Related Art
A semiconductor wafer (hereinafter, simply referred to as “wafer”) is thinned by processing by using a mechanical method such as grinding or polishing, or a chemical method using etching. At the time of processing the wafer by using any of the methods, a protective tape is joined to a surface of the wafer to protect the surface on which a wiring pattern is formed. The wafer to which the protective tape is joined and which is grinded is adhered and held from a back side thereof to a ring frame by way of a dicing tape. The protective tape is then separated and removed from the surface of the wafer held by the ring frame.
As a method for separating and removing the protective tape, there is known a method for joining the separation tape to the surface of the protective tape with a roller-shaped joining member, and separating the separation tape, thereby separating and removing to wind the protective tape integrally from the surface of the wafer (see e.g., Japanese Laid-Open Patent Publication No. 5-63077).
The above-mentioned conventional protective tape separation method, however, has the following problems.
In a case where adherence of the protective tape with respect to the wafer is higher, it becomes difficult to form at a peripheral edge of the wafer a fold-back site that serves as a start of separating the protective tape even when the separation tape joined to the protective tape is separated. The protective tape thus cannot be separated.
Furthermore, a cut plane of the protective tape cut in a protective tape cutting step is an inclined surface (trapezoidal) of which width becomes wider from the surface of the protective tape towards an adhesion surface of the wafer. Thus, it becomes difficult to adhere the separation tape to the peripheral edge of the protective tape, whereby a separation stress is less likely to be applied during separation and separation cannot be carried out with satisfactory precision.
Tight adherence of the separation tape to the peripheral edge of the protective tape can be realized by strongly pressing the separation tape with the roller-shaped joining member. However, the wafer processed to be thin may be damaged in a case where the pressing force is increased.